about tam-tara size of the p1-p2, it did become smaller because people was feeling it was too big and some people even get lost into it. you have almost 2 time the number of pack you have now.



that said, the open world content (the one that everybody can enter without instance) can lead to many trouble, like if the place is over-populate by the player, leading to some area totally barren. it happend in game with open world content, let's take an example look the tribes daily area, around the reset, this area have more player than monster in the area. (almost a ratio of 3-4 player for 1 monster) it's absurd, it loose all credibility and challenge.
let's say they add an area that ask people to group for do it. people will farm it, until something better come out and what will happend? the place will be empty of player and find people for do it will be extremely hard.

the advantage of the instance is, if no one use it, the instance server don't generate the area, in the open world this area is always generate and it take space on it.
don't get me wrong, i want more stuff related to the world, but actually open world content have a lot of flaws. mostly because of the number of people per server. if they add a new high level area, they need to make it bigger enough for contain all player...